At AGU: Shale sequestration, water for energy & soil microbes

PNNL research is digging into using empty space in underground shale formations to permanently store carbon emissions from power plants. This map shows where shale gas formations (purple dots) are near carbon-emitting power plants (orange dots).

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Scientists from the Department of Energy's Pacific Northwest National Laboratory will present a variety of their research at the 2013 American Geophysical Union Fall Meeting, which runs Monday, Dec. 9 through Friday, Dec. 13 at the Moscone Convention Center in San Francisco. Among the noteworthy PNNL research scheduled to be discussed are carbon sequestration in empty shale reservoirs, water needs for future energy production and how soil microbes adjust to climate change. More information is below.

Shale formations — underground mixes of mud, minerals and gas that have sparked a natural gas drilling boom in the United States — could also help power plants meet proposed EPA emission regulations by permanently storing carbon dioxide. But while many pollution-emitting power plants are located near shale formations, little is known about the complex chemistry of shales reacting with pumped-in carbon emissions. The issue is complicated by the variety of different clay minerals that make up shales. PNNL scientists are getting to the bottom of these details by conducting laboratory experiments and computer modeling research to determine how carbon dioxide, methane and common power plant byproducts such as sulfur dioxide react with the four clays common in shales. Early results show the clay mineral montmorillonite expands to hold more carbon emissions under certain conditions. Tests also show the clay kaolinite has a sweet spot to absorb emissions with an ideal combination of pressure and carbon dioxide concentrations. PNNL geologist Todd Schaef will present these and other results, including a preliminary cost-benefit analysis of carbon sequestration at the United States' shale gas reservoirs.

Future power plants can use more water-efficient cooling technologies to withdraw less water from rivers and ponds, but PNNL research shows there is a tradeoff. Water-efficient cooling technologies typically reuse water instead of using it just once, but they also warm the reused water and cause evaporation that removes water from the local ecosystem. PNNL used a computer model to estimate future energy generation and associated water use for each of the 50 states. The detailed analysis found while the nation's energy sector could withdraw less water with advanced cooling technologies, the amount of water consumed through evaporation would increase. The study also identified several other trends, such as energy-related water withdrawals decreasing in the Eastern U.S. while they increase in the West. PNNL environmental scientist Lu Liu will present a poster on this research.

H11J-1274: "An integrated assessment of energy-water nexus at the state level in the United States: Projections and analyses under different scenarios through 2095," 8 a.m.-12:20 p.m., Tuesday, Dec. 10, Hall A-C (Moscone South).

Climate change alters bacteria behavior

Climate change doesn't affect just polar bears and ice caps; it also impacts the tiny microbes that help plants soak up nutrients in the soil. New research shows transplanted soil bacteria adjust their enzyme production to better survive in a new climate. The findings are a result of a unique study where soil samples were transplanted between two elevations about 1700 feet apart on an isolated mountain in rural Washington state. The scientists gave the transplanted soil about 17 years to settle into its new surroundings and then compared its bacteria with bacteria in unmoved soil samples. The researchers found bacteria made more of some enzymes in the higher-up soil, where it's wetter and cooler and there's more vegetation. The enzymes found in greater abundance break down cellulose — the tough, pithy material that gives plants structure — and chitin — another tough material that strengthens fungal cell walls. The researchers hypothesize the higher-elevation bacteria produce more of those enzymes because the richer soils there are home to more plants and fungi for the bacteria to digest. Better understanding how climate impacts microbes can also help us better understand climate change, as many of the greenhouse gases that contribute to climate change occur as a result of interactions with microbes. PNNL microbiologist Vanessa Bailey will present a poster on this research.

Interdisciplinary teams at Pacific Northwest National Laboratory address many of America's most pressing issues in energy, the environment and national security through advances in basic and applied science. Founded in 1965, PNNL employs 4,300 staff and has an annual budget of more than $1 billion. It is managed by Battelle for the U.S. Department of Energy's Office of Science. As the single largest supporter of basic research in the physical sciences in the United States, the Office of Science is working to address some of the most pressing challenges of our time. For more information on PNNL, visit the PNNL News Center, or follow PNNL on Facebook, Google+, LinkedIn and Twitter.